Can be found on the second map in front of the blue teleporter when coming from the purple one.

X360 & PC: Is always present.

PC Glitch Note: Sometimes Falak will be invisible, as if it didn't spawn. When this happens you can walk right over its spawn point without encountering it. However, you can Timeshift at its location, link it (you'll hear the link sound), then start the battle to fight it. Alternatively, you can save your game inside the Sacred Lands, then reload it; this causes it to appear and properly function in the level.